A randomized controlled trial of cervical cerclage in women at high risk of spontaneous preterm delivery

Upregulated amniotic fluid cytokines and chemokines in emergency cerclage with protruding membranes

PROBLEM  To identify the prognostic factors for pregnancy outcome in women who received emergency cerclage for dilated cervix with protruding membranes. METHOD OF STUDY  A prospective cohort study was performed, and a total of 14 women who received emergency cerclage were included. Clinical features and laboratory findings including amniotic fluid cytokines and chemokines were compared between women who had successful pregnancy (survival group, n = 6) and those who had perinatal death (non-survival group, n = 8). Five healthy pregnant women served for normal controls for amniotic fluid study. RESULTS  The overall neonatal survival was 42.9% in women with emergency cerclage. Serum C-reactive protein levels on postoperative day 3 and 7 were significantly higher in non-survival group when compared with those in survival group (P = 0.002, P = 0.01). Amniotic fluid levels of interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α, and monocyte chemoattractant protein-1 levels of the patients were significantly higher than those of normal controls. Amniotic fluid levels of IL-1α, IL-1β, and IL-8 were significantly increased in the non-survival group when compared with those of the survival group. CONCLUSION  Systemic and local inflammatory markers including proinflammatory cytokines and chemokines may predict pregnancy outcome in women with emergency cerclage for dilated cervix with protruding membranes.

Care for women with prior preterm birth

Women who have delivered an infant between 16 and 36 weeks' gestation have an increased risk of preterm birth in subsequent pregnancies. The risk increases with more than 1 preterm birth and is inversely proportional to the gestational age of the previous preterm birth. African American women have rates of recurrent preterm birth that are nearly twice that of women of other backgrounds. An approximate risk of recurrent preterm birth can be estimated by a comprehensive reproductive history, with emphasis on maternal race, the number and gestational age of prior births, and the sequence of events preceding the index preterm birth. Interventions including smoking cessation, eradication of asymptomatic bacteriuria, progestational agents, and cervical cerclage can reduce the risk of recurrent preterm birth when employed appropriately.

Prematurity prevention: the role of cerclage

PURPOSE OF REVIEW

To summarize the literature on the value of cervical cerclage for the prevention of preterm birth and present the recent advances in its clinical application.

RECENT FINDINGS

The diagnosis of cervical insufficiency is difficult as there are no objective diagnostic criteria. Although widely used, the value of cervical cerclage is still a matter of controversy. The current literature suggests that cerclage placement can prevent preterm delivery in women with a history of at least three second-trimester losses or at least three preterm births and in those with a history of prematurity who have a cervical length of less than 25 mm in the second trimester. It is also possible to improve the perinatal outcome in patients with cervical dilation in the mid-trimester. It is not indicated in multiple pregnancies, however. Further research is needed in methods of excluding inflammation in women with cervical changes on ultrasound prior to cerclage insertion. Transabdominal or laparoscopic cerclage seems to be a promising alternative in women with a history of transvaginal cerclage failure.

SUMMARY

Strict recommendations on the proper use of cerclage cannot be easily made. Data from randomized trials do not support what the current practice in many cases is.

Prevention of preterm birth based on a short cervix: cerclage

In an attempt to prevent preterm birth, clinicians have recommended cerclage for women with shortened cervical length and other worrisome sonographic cervical features in the mid-trimester, although randomized trials have not supported this practice. Emerging data suggest that preterm birth is a complex and poorly understood syndrome comprising several anatomic and functional components. As a result, preventive efforts have been mostly empiric and generally ineffective. Plausibly, effective preterm birth therapies exist, but matching the effective treatment with the correct patient has been problematic. Mid-trimester cervical changes visualized with vaginal sonography likely represent a pathologic process of premature cervical ripening and not real mechanical disability which has been traditionally treated with suture support. Cerclage may effectively reduce preterm birth in carefully selected women who have experienced a prior early preterm birth and who have shortened mid-trimester cervical length.

Prevention of PPROM: Current and future strategies

Our understanding of the pathophysiologic processes leading to preterm premature rupture of membranes (PPROM) has grown tremendously in recent years. Evidence suggests that there may be a genetic susceptibility to PPROM and that genetic and environmental elements are important cofactors in its development. A number of risk-based protocols have been proposed in an attempt to identify those women at highest risk for PPROM. While we have made advances in the area of predicting PPROM, treatments based on current risk-based systems have failed to distinguish a specific, effective preventive therapy for PPROM. The concept that genetic factors increase susceptibility or decrease resistance to disease has stimulated new work in the field of PPROM. Several maternal and fetal gene polymorphisms have been identified that are associated with an increased risk for PPROM. Patients with 'susceptible' genotypes may also have clinical risk factors for PPROM resulting in a synergistic increase in the risk for PPROM, a so-called gene-environment interaction. The concept that these gene-environment interactions represent new targets for our efforts to prevent PPROM is explored.

Goals and strategies for prevention of preterm birth: an obstetric perspective

Complications of prematurity surpass congenital malformations as the leading cause of infant mortality in the United States. Since 1990, there has been a steady rise in preterm birth, alarming health professionals from all disciplines. This review from a prenatal perspective confirms those concerns and describes the risks and opportunities that may attend efforts to improve the health of fetuses, newborns, and infants. Fetal and live-born outcomes are included.

Demographics and outcome of elective cerclage in a multi-ethnic London district general hospital

Elective cerclage is a rare procedure, but is reported to be relatively more common in developing countries. This variation in rate may be reflected in a multi-ethnic population as seen in London. Our study analysed the epidemiology and rate of elective cerclage performed in a London district general hospital. Factors contributing to the outcome of the procedures were also reviewed. A total of 41 elective cerclages were performed in the hospital between 2000 and 2007. Data from these were collected retrospectively, including maternal history, operative details, and gestational age at delivery. Fisher's exact test was used for statistical analysis. Of the 41 cases, 19 pregnancies were carried to term (>or=37 weeks' gestation), nine were pre-term (24-36 weeks' gestation) and seven miscarried (<24 weeks' gestation); six cases had not yet delivered. All of the patients were immigrants from developing countries but ethnicity did not affect the operative outcome (p = 0.89, Fisher's exact). The other factors studied were also noted to have no significant impact on success. These included cervical length at insertion (p = 1.00, Fisher's exact), type of suture (p = 0.90, Fisher's exact) and average gestation at insertion (p = 0.20, Fisher's exact). In conclusion, all patients requiring intervention in this study originated from developing countries. This is a disproportionately high figure relative to the demographic breakdown of the study population. Such a finding may be due to geographical variation of risk factors for cervical incompetence but may also be influenced by observer bias. Additional studies are needed to further investigate the influence of ethnicity on the rate of elective cerclage. None of the variables analysed in this study significantly affected the outcome of the procedure.

History-indicated cerclage: practice patterns of maternal-fetal medicine specialists in the USA

OBJECTIVE

There is limited evidence supporting the effectiveness of history-indicated cerclage in preventing spontaneous pregnancy loss or preterm birth. This study was undertaken to estimate the practice patterns of maternal-fetal medicine specialists in regards to history-indicated cerclage.

METHODS

We performed a mail-based survey of all SMFM specialists in the US. Subjects were asked whether they would recommend a history-indicated cerclage at 12-14 weeks in a patient whose prior pregnancy was her first pregnancy and ended in a spontaneous, painless loss at 19 weeks with no identifiable cause.

RESULTS

A total of 827 (46%) of SMFM members responded of which 75% would recommend a history-indicated cerclage for this patient. Twenty-one percent would not recommend one, but would place one if desired by the patient. Only 4% would not place a history-indicated cerclage in this scenario. A total of 71% believed a history-indicated cerclage was associated with moderate or significant benefit, and 89% believed it involved minimal or no risk. Female gender, non-academic practice, practicing in the southern region and greater interval since residency training were all independently associated with the recommendation for a history-indicated cerclage.

CONCLUSIONS

Despite limited level-I evidence supporting its use, a history-indicated cerclage is recommended by most maternal-fetal medicine specialists.

Prevention of preterm birth

For an infant without lethal congenital malformations there is no risk greater than to be born too early. In addition, preterm birth with its many consequences may compromise the life of the whole family. Thus, prevention of preterm birth is one of the greatest challenges in obstetrics. However, this has proven to be difficult. This difficulty is in part due to the fact that, although we know a large number of clinical factors which are know a large number of clinical factors which are associated with preterm birth, the final mechanisms triggering the onset of preterm contractions or premature rupture of the fetal membranes (PROM) have remained largely unclear. We review the prevention of preterm birth in the light of the newest data; an interested reader is also referred to other recent overviews on the same topic.

Management of painless mid-trimester cervical dilatation: Prophylactic vs emergency placement of cervical cerclage

Women with recurrent painless mid-trimester miscarriages are often diagnosed with cervical insufficiency. Presenting symptoms typically include vaginal pressure and minimal bleeding; when the cervix is examined, advanced dilatation is usually detected. Labour is short and the premature fetus is born alive. Women with this history were traditionally considered candidates for the placement of cervical cerclage. Recently, this practice has been called into question. Rather than routine placement of prophylactic cervical cerclage at 12 - 14 weeks, many patients are followed expectantly with serial sonographic assessments of cervical length. The goal of this update is to review the literature regarding management options of mid-trimester cervical dilatation.

Effect of 2 stitches vs 1 stitch on the prevention of preterm birth in women with singleton pregnancies who undergo cervical cerclage

OBJECTIVE

This study investigates whether 2 cerclage stitches are more effective than 1 stitch in the prevention of preterm birth.

STUDY DESIGN

This is a retrospective cohort study of 150 singleton pregnancies that underwent cervical cerclage. Gestational age at delivery and clinical characteristics were compared.

RESULTS

One hundred twelve patients (74.7%) received 1 stitch, and 38 patients (25.3%) received 2 stitches. There were no baseline differences between the groups. Analysis showed no significant difference in gestational age at delivery between the 1 vs 2 cerclage groups overall (median, 38.0 vs 38.3 weeks of gestation, respectively; P = .356) or for a given gestational age cut-off (<37 weeks of gestation: 37.4% vs 34.2% [P = .727]; <34 weeks of gestation: 16.8% vs 18.4% [P = .823]; <28 weeks of gestation: 9.4% vs 2.6% [P = .179]).

CONCLUSION

This study shows no measurable benefit to the placement of 2 stitches over 1 stitch during cervical cerclage in singleton pregnancies; however, further study of preterm birth at <28 weeks of gestation and postcerclage outcomes among a larger cohort is merited.

Tightening McDonald cerclage suture under sonographic guidance

OBJECTIVE

The technical factors contributing to failure of cerclage are not fully understood. The aims of this study were to assess the possibility of tightening the McDonald cerclage under ultrasound guidance and to examine the width and shape of the cervical canal before and after tightening the suture.

METHODS

A prospective study was performed. The sole indication for cerclage placement was clinical history of cervical insufficiency. Cervical length and canal width were measured by transvaginal ultrasound, at 12-14 weeks' gestation, with the patient's bladder empty, after which the cerclage was performed. Tightening of the suture was performed under sonographic guidance (transabdominal or transrectal) until the cervical canal disappeared from view. After tying the suture, cervical length and the canal width were assessed sonographically.

RESULTS

Fifty-eight patients were enrolled in the study; 50 patients had singleton pregnancies and eight patients carried twins. The mean cervical length at the beginning of the procedure was 31 +/- 13 mm (median 30 mm, range 15-48 mm). The mean cervical canal width was 2.1 +/- 0.9 mm (median 2.0 mm, range 0.9-4.5 mm). The mean addition to the length of the cervical canal after the procedure was 11 +/- 0.8 mm (median 1.0, range 8-19 mm). No complications were noted during the procedures. An interesting sonographic finding was an hourglass shape of the cervical canal after the procedure in 16 patients. Of 58 patients, 47 delivered at term, 10 delivered preterm and one miscarried at 18 weeks. Nine of 10 patients with preterm delivery had an hourglass-shaped sonographic appearance of the cervical canal after the procedure.

CONCLUSIONS

McDonald cerclage can be tightened under ultrasound guidance. The sonographic appearance of an hourglass shape of the cervical canal following suture tightening may be a risk factor for preterm delivery.

Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth

Interventions to reduce the morbidity and mortality of preterm birth can be primary (directed to all women), secondary (aimed at eliminating or reducing existing risk), or tertiary (intended to improve outcomes for preterm infants). Most efforts so far have been tertiary interventions, such as regionalised care, and treatment with antenatal corticosteroids, tocolytic agents, and antibiotics. These measures have reduced perinatal morbidity and mortality, but the incidence of preterm birth is increasing. Advances in primary and secondary care, following strategies used for other complex health problems, such as cervical cancer, will be needed to prevent prematurity-related illness in infants and children.

Expectant management compared with physical examination-indicated cerclage (EM-PEC) in selected women with a dilated cervix at 14(0/7)-25(6/7) weeks: results from the EM-PEC international cohort study

OBJECTIVE

The objective of the study was to compare pregnancy outcomes in selected women with a dilated cervix who underwent expectant management or physical examination-indicated cerclage.

STUDY DESIGN

This was a historical cohort study conducted by the Global Network for Perinatal and Reproductive Health. Women between 14(0/7) and 25(6/7) weeks' gestation with a dilated cervix were identified at 10 centers by ultrasound or digital examination. Primary outcome was time from presentation until delivery (weeks). Secondary outcomes were neonatal survival, birthweight greater than 1500 g and preterm birth less than 28 weeks. Multivariate regression was used to assess the likelihood of neonatal outcomes and control for confounders.

RESULTS

Of 225 women, 152 received a physical examination-indicated cerclage, and 73 were managed expectantly without cerclage. Cervical dilation, gestational age at presentation, and antenatal steroid use differed between groups. In the adjusted analyses, cerclage was associated with longer interval from presentation until delivery, improved neonatal survival, birthweight greater than 1500 g and preterm birth less than 28 weeks, compared with expectant management. Similar results were obtained in the analyses limited to women dilated between 2 and 4 cm (n = 122).

CONCLUSION

In this study, the largest cohort reported to date, physical examination-indicated cerclage appears to prolong gestation and improve neonatal survival, compared with expectant management in selected women with cervical dilation between 14(0/7) and 25(6/7) weeks. A randomized, controlled trial should be conducted to determine whether these potential benefits outweigh the risks of cerclage placement in this population.

Systematic review: Cervical stitch (cerclage) for preventing pregnancy loss: individual patient data meta-analysis

BACKGROUND

Several observational studies have claimed high success rates for cerclage in women with cervical insufficiency. A recent Cochrane review found no conclusive evidence of benefit, although significant heterogeneity was present for some of the important clinical outcomes.

OBJECTIVES

We undertook an individual patient data (IPD) meta-analysis to examine effect of cerclage on neonatal and maternal outcomes. In an attempt to explain the heterogeneity, we investigated whether obstetric factors including multiple gestation are associated with effectiveness.

SEARCH STRATEGY

Search methods described in the original Cochrane review were adopted and updated to December 2005.

SELECTION CRITERIA

This IPD systematic review and meta-analysis was of randomised trials comparing cervical cerclage during pregnancy with expectant management or no cerclage in women with confirmed or suspected as having cervical insufficiency.

ANALYSIS

Multilevel logistic regression models stratified by trial with random treatment effects were fitted to investigate the impact of obstetric factors and multiple gestation on treatment effect. Primary outcome measures were pregnancy loss or death before discharge from hospital and absence of neonatal morbidity.

MAIN RESULTS

The meta-analysis included seven trials and 2091 randomised women. In singleton pregnancies, the reduction in pregnancy loss or death before discharge from hospital following cerclage failed to reach statistical significance (OR 0.81; 95% CI 0.60-1.10). Cerclage was found to have a detrimental effect on the outcome of pregnancy loss or death before discharge from hospital in multiple gestations (OR 5.88; 95% CI 1.14-30.19), although only a small number of multiple pregnancies were included in the analysis. Neither indication for cerclage nor obstetric history was found to have a statistically significant impact on the effect of cerclage.

CONCLUSIONS

Cerclage may reduce the risk of pregnancy loss or neonatal death before discharge from hospital in singleton pregnancies thought to be at risk of preterm birth, but further large trials are needed to elucidate the risk-benefit ratio precisely. Cerclage in multiple pregnancies should be avoided. The efficacy of cerclage was not influenced by either indication for cerclage or mother's obstetric history.

Recurrent preterm birth

Recurrent preterm birth is frequently defined as two or more deliveries before 37 completed weeks of gestation. The recurrence rate varies as a function of the antecedent for preterm birth: spontaneous versus indicated. Spontaneous preterm birth is the result of either preterm labor with intact membranes or preterm prelabor rupture of the membranes. This article reviews the body of literature describing the risk of recurrence of spontaneous and indicated preterm birth. Also discussed are the factors which modify the risk for recurrent spontaneous preterm birth (a short sonographic cervical length and a positive cervicovaginal fetal fibronectin test). Patients with a history of an indicated preterm birth are at risk not only for recurrence of this subtype, but also for spontaneous preterm birth. Individuals of black origin have a higher rate of recurrent preterm birth.

Contemporary Use of Cervical Cerclage

Although it was devised over 50 years ago, only recently controlled randomized trials have evaluated the efficacy of cervical cerclage. Cerclage was originally devised for women with both prior preterm birth (PTB) and cervical changes in the current pregnancy. Evidence suggests that transvaginal cerclage probably prevents second trimester loss/PTB in women with >or=3 PTB/second trimester loss (history-indicated cerclage best placed at 12 to 14 wk); and in women with a prior PTB 16 to 36 weeks and transvaginal ultrasound cervical length<25 mm in the current pregnancy (ultrasound-indicated cerclage at 14 to 23 6/7 wk).

Cervical cerclage in the prevention of preterm birth

Cervical cerclage has been used in the management of cervical insufficiency for several decades, yet the indications are uncertain and benefits marginal. It remains a controversial intervention. The diagnosis of cervical insufficiency is traditionally based on a history of recurrent second trimester miscarriages, or very preterm delivery whereby the cervix is unable to retain the pregnancy until term. Cervical cerclage has been the subject of many observational and randomised controlled trials. This article reviews the literature regarding the effectiveness of elective or emergency transvaginal cerclage and transabdominal cerclage.

Preterm labour. Cervical function and prematurity

The cervix maintains the fetus in situ during pregnancy and dilates during labour to allow delivery of the baby. Congenital or iatrogenically-induced structural abnormalities of the cervix are associated with an increased risk of preterm birth. The role of cervical infection is less clear. Cervical studies may be useful in the prediction of preterm delivery: both a shortened cervical length identified on transvaginal ultrasound examination and an increased level of fetal fibronectin in cervico-vaginal secretions are associated with an increased risk of preterm delivery. In singleton pregnancy, cervical cerclage reduces the risk of preterm birth by 25%. There is no evidence of a reduction in neonatal mortality or morbidity, and the beneficial effects of preterm birth reduction have to be set against the increased risk of maternal infection. Neither the American College of Obstetricians and Gynecologists (ACOG) nor the Royal College of Obstetricians and Gynaecologists (RCOG) has unequivocally endorsed cervical cerclage. Further work is required to define the role of the cervix in prediction and prevention of spontaneous preterm birth.

Could a cervical occlusion suture be effective at improving perinatal outcome?

Cervical weakness and infection have long been regarded as major causes of preterm birth. Cervical cerclage has been used extensively to reduce the risk of preterm birth arising as a result of cervical weakness, but increasing evidence suggests that the cervix plays more than just a mechanical role. Immunological function of the cervix and mucus plug is thought to be important in minimising the ingress of microbes, which can lead to chorioamnionitis and rupture of the amniotic membranes. In this review, we examine the background of traditional cervical cerclage and introduce the concept of the occlusion suture and its potential benefit in reducing the risk of recurrent preterm prelabour rupture of membranes.

PREMATURE CERVICAL CHANGE AND THE USE OF CERVICAL CERCLAGE

Preterm birth and its subsequent consequences continue to be a major challenge worldwide. In the United States in 2004, 12.5% of infants were born preterm, making the annual societal economic burden associated with preterm birth in excess of $26.2 billion (and this is a modest estimate). Spontaneous preterm birth accounts for about 75% of all preterm births; however, at earlier gestations iatrogenic preterm birth accounts for a greater proportion of all preterm births; at 27–28 weeks 50% are iatrogenic. The proportion of babies transferred to the neonatal unit is more than 90% for those born before 33 completed weeks of gestation compared with 31% at 36 weeks; delivery between 33 completed weeks and 36 completed weeks has a relatively low morbidity and mortality. Nonetheless, 1 in 3 children born preterm but beyond 32 weeks have educational and behavioural problems at the age of 7, with 1 in 4 children born between 32 and 35 weeks requiring support from non-teaching assistants at school. Although more than 40% of babies at 35 completed weeks show signs of maturity, some still need ventilation at 38 completed weeks. Almost one-fifth of all infants born at less than 32 weeks gestation do not survive the first year of life.

Preterm labour: update on prediction and prevention strategies

PURPOSE OF REVIEW

The incidence of preterm birth is increasing and continues to be a significant cause of neonatal mortality and morbidity. Techniques now exist that can accurately predict early birth. Prevention can therefore be targeted, although effective measures that improve outcome are yet to be established.

RECENT FINDINGS

Obtaining an accurate history is the first step in identifying high-risk women. Clinicians then rely on other predictors such as fetal fibronectin, cervical length assessment and biochemical markers. Research should focus on the combination of noninvasive markers targeted at high-risk women as a screening tool, determining not only appropriate diagnostic levels for positive tests, but also sufficiently large studies should be performed to determine the predictive values of these tests. Interventions to prevent delivery and improve neonatal outcome remain unsatisfactory, mainly comprising tocolysis, cerclage, progesterone and, in some cases, antibiotics. Women who would most benefit from these interventions are difficult to identify and an appreciation of the pathophysiology in an individual woman, such as the relevance of the inflammatory status of the endocervix, may be important in tailoring intervention.

SUMMARY

An improved understanding of the mechanisms underlying the pathological process in preterm birth will allow screening and interventions to be appropriately targeted.

Management of Cervical Insufficiency and Bulging Fetal Membranes

OBJECTIVE

To evaluate the efficacy of emergency cerclage in cases with dilated cervix and protruding fetal membranes in a group of women considered at low risk for preterm delivery by their obstetric histories.

METHODS

All cases of cervical dilatation and bulging membranes were detected through a transvaginal ultrasonographic screening for preterm delivery between 18 and 26 weeks during a 6-year study period. Twenty-nine women underwent an emergency cervical cerclage and composed the cerclage group, whereas 17 others refused and formed the bed rest group. All patients were given antibiotics and prophylactic tocolysis.

RESULTS

The mean prolongation of pregnancy (8.8 weeks) and the mean birth weight (2,101 g) after cerclage placement differed significantly from those of the bed rest group (3.1 weeks and 739 g, respectively). Twenty-five of the 29 pregnancies in the cerclage group ended in live birth, compared with 7 of the 17 pregnancies in the bed rest group (P = .001) (relative risk [RR] 0.33, 95% confidence interval [CI] 0.11-0.98). Neonatal survival was 96% in the cerclage group and 57.1% in the bed rest group (P = .025) (RR 0.09, 95% CI 0.01-0.76). The preterm delivery rate less than 32 weeks was 31% and 94.1% in the cerclage and the bed rest groups, respectively (P < .001) (RR 0.33, 95% CI 0.19-0.57), whereas the admission to neonatal intensive care unit was 28% and 85.7% in the 2 groups, respectively, (P = .01) (RR 0.33, 95% CI 0.16-0.66).

CONCLUSION

Emergency cervical cerclage can be accomplished safely in women with dilated cervix and bulging membranes. It can reduce preterm delivery before 32 weeks and improve neonatal survival compared with bed rest.

LEVEL OF EVIDENCE

II-1.

The role of cervical cerclage in obstetric practice: can the patient who could benefit from this procedure be identified?

This editorial critically examines the definition of "cervical insufficiency." The definition, the clinical ascertainment, efforts to develop an objective method of diagnosis, as well as the nature of cervical disease leading to spontaneous mid-trimester spontaneous abortion and preterm delivery are reviewed. The value and limitations of cervical sonography as a risk assessment tool for spontaneous preterm delivery are appraised. The main focus is on the role of cervical cerclage to prevent an adverse pregnancy outcome. The value of assessing the presence or absence of endocervical inflammation in the outcome of cerclage placement is discussed.

Evaluation of effectiveness of prophylactic cerclage of a short cervix according to interleukin-8 in cervical mucus

OBJECTIVE

This study was undertaken to compare rates of preterm delivery according to cervical mucus interleukin-8 (IL-8) among women who underwent cerclage because of a short cervix.

STUDY DESIGN

This retrospective study included 16,508 patients whose cervical length and cervical mucus IL-8 concentrations were measured between 20 and 24 weeks. A short cervix was defined by a length of 25 mm or less, whereas IL-8 concentrations exceeding 360 ng/mL were considered high. Whether to perform cerclage was decided by clinicians without consideration of IL-8 concentrations.

RESULTS

Among all subjects, a significantly smaller percentage of subjects avoided delivery before 37 weeks when cervical mucus IL-8 was elevated (P = .0302) or the cervix was short (P < .0001). Among patients with a short cervix, preterm delivery was more likely when cervical mucus IL-8 was elevated. Overall, risk of preterm delivery in patients with a short cervix did not differ between those undergoing and not undergoing cerclage. However, among patients with a short cervix, those with normal IL-8 concentrations in cervical mucus were less likely to have preterm delivery if they underwent cerclage (before 37 weeks, 33% vs 54.5%, P = .01; before 34 weeks, 4% vs 13.6%, P = .03). In contrast, when cervical mucus IL-8 was high, delivery before 37 weeks was more likely with than without cerclage (78% vs 54.1%, P = .03).

CONCLUSION

With normal cervical mucus IL-8, cerclage treatment for cervical shortening may reduce the rate of preterm delivery, but with elevated cervical mucus IL-8 cerclage may be harmful.

Does cerclage prevent preterm birth?

Cerclage procedures can be classified according to timing, (elective, urgent, emergent), and anatomic approach (transvaginal and transabdominal). The most current clinical data and the evidence-based recommendations for each type of cerclage procedure are listed.

Cerclage for Short Cervix on Ultrasonography

OBJECTIVE

Preterm birth is the main cause of perinatal morbidity and mortality. A short cervical length on transvaginal ultrasonography predicts preterm birth. Our aim was to estimate by meta-analysis of randomized trials whether cerclage prevents preterm birth in women with a short cervical length.

DATA SOURCES

MEDLINE, PubMed, EMBASE, and the Cochrane Library were searched with the terms "cerclage," "cervical cerclage," "short cervix," "ultrasound," and "randomized trial." We included randomized trials involving the use of cerclage in women with short cervical length on transvaginal ultrasonography using patient-level data.

TABULATION, INTEGRATION, AND RESULTS

Four properly conducted trials were identified. In the total population, preterm birth at less than 35 weeks of gestation occurred in 29.2% (89/305) of the cerclage group, compared with 34.8% (105/302) of the no-cerclage groups (relative risk [RR] 0.84, 95% confidence interval [CI] 0.67-1.06). There was no significant heterogeneity in the overall analysis (P = .29). There was a significant reduction in preterm birth at less than 35 weeks in the cerclage group compared with the no-cerclage groups in singleton gestations (RR 0.74, 95% CI 0.57-0.96), singleton gestations with prior preterm birth (RR 0.61, 95% CI 0.40-0.92), and singleton gestations with prior second-trimester loss (RR 0.57, 95% CI 0.33-0.99). There was a significant increase in preterm birth at less than 35 weeks in twin gestations (RR 2.15, 95% CI 1.15-4.01).

CONCLUSION

Cerclage does not prevent preterm birth in all women with short cervical length on transvaginal ultrasonography. In the subgroup analysis of singleton gestations with short cervical length, especially those with a prior preterm birth, cerclage may reduce preterm birth, and a well-powered trial should be carried out in this group of patients. In contrast, in twins, cerclage was associated with a significantly higher incidence of preterm birth.

Cerclage for the short cervix demonstrated by transvaginal ultrasound: current practice and opinion

OBJECTIVES

(1) To elucidate the views of obstetricians with respect to the use of transvaginal ultrasound in general, and, specifically, for determining cervical length, and the conditions under which obstetricians would employ cervical cerclage based on a sonographically revealed shortened cervix; and (2) to determine the possibility of a randomized controlled trial on the use of cervical cerclage in this situation.

METHODS

A 7-item questionnaire in French and English was designed and pretested. Questionnaires were mailed to 1421 physicians identified in the Canadian Medical Directory as practising obstetricians/gynaecologists in Canada. Returned questionnaires were scanned into an Access database for simple descriptive analyses.

RESULTS

Responses were received from 766 physicians. Of these 766 respondents, 604 physicians indicated they continued to practise obstetrics and supplied information that was usable in the analysis. The majority of the 604 respondents (85.6%) reported that they would recommend transvaginal ultrasound only in pregnant women with 1 or more risk factors for preterm birth. Respondents were most likely to recommend a cerclage, and least unsure of their decision to do so, if the gestational age was less than 23 weeks, the cervical length was less than 1 cm, and additional risk factors for preterm birth were present. As gestational age and cervical length increased, respondents were less likely to recommend cerclage and more unsure of their decision to do so. The pattern of responses was similar for singleton and multiple pregnancies. The McDonald technique was favoured over the Shirodkar technique by 70.4% of the respondents who performed cervical cerclage procedures. Adjunctive antibiotics were used with cerclage by 52.5% and adjunctive tocolytics were employed by 37.4%. The majority (68.8%) of the respondents who performed cervical cerclage procedures stated that they would participate in a randomized controlled trial on the effectiveness of cerclage for a sonographically revealed short cervix.

CONCLUSION

In the case of a short cervix determined by ultrasound, there is significant uncertainty surrounding the decision whether to place a cerclage and considerable variation in the clinical practice on its placement. In the absence of good evidence to guide clinical practice, a randomized controlled trial is being planned.

Does the presence of a funnel increase the risk of adverse perinatal outcome in a patient with a short cervix?

OBJECTIVE

This study was undertaken to determine whether the presence of a dilated internal os (funneling or beaking) alters the outcome of patients with a short cervix documented by transvaginal ultrasound in the second trimester.

STUDY DESIGN

Between January 1998 and May 2004, all singleton pregnancies with a short cervix (< or =2.5 cm) and no funnel between 16 and 24 weeks' gestational age were identified by query and review of the Lehigh Valley Perinatal Ultrasound Database. These no funnel patients were compared with patients with a short cervix and funnel matched in accordance with cervical length and risk factors. Multiple variables of perinatal outcome were identified and compared between the Funnel and No Funnel groups. Correlations between cervical measurements and gestational age at birth were analyzed.

RESULTS

Of the 279 patients with a short cervix identified, 82 were singleton with a T-shaped cervix and no funnel and 82 patients matched with a typical Y-shaped funnel. There was no difference between groups with respect to maternal demographics, previous preterm birth (28.1% No Funnel group vs 36.5% Funnel group, P = .3), prior cervical surgery (24.3% vs 22.0 %, P = .8), gestational age at entry (20.5 +/- 2.1 vs 21.1 +/- 2.4 weeks, P = .1), and cervical length (1.9 +/- 0.4 vs 1.8 +/- 0.5 cm , P = .1). The No Funnel group had significantly less readmissions for preterm labor (43.2% vs 67.1 %, P = .004), chorioamnionitis (2.4% vs 23.2 %, P = .0002), abruption (1.2% vs 13.4 %, P = .007), preterm rupture of membranes (6.1% vs 23.4%, P = .002), and cerclage placement (23.2% vs 43 %, P = .008). The neonates in the no funnel group delivered later (36.2% +/- 4.6 vs 33.8 +/- 5.4 weeks , P = .003), and had less morbidity and mortality (17.1% vs 37.8 %, P = .02) compared with the Funnel group. The width and depth of the funnel did not correlate with perinatal outcome. Cervical length ( R(2) = 0.07, P = .02) and cervical funneling as a categorical variable ( r = 0.3, P = .0002) did correlate with earlier delivery.

CONCLUSION

The disruption of the internal os, as documented by funneling, is a significant risk factor for adverse perinatal outcome (ie, preterm labor, chorioamnionitis, abruption, rupture of the membranes, and serious neonatal morbidity and mortality). Cervical funneling is best measured as a categorical variable (present or absent).

Strategies for prevention-cervical cerclage

Transvaginal cervical cerclage was introduced as a treatment for cervical incompetence in 1951. Over the years, our understanding of this clinical entity has changed tremendously, which has implications for obstetric management. This review focuses on the obstetric management of women considered to be at high risk of preterm delivery due to cervical incompetence at different stages of pregnancy.

Controversies regarding cervical incompetence, short cervix, and the need for cerclage

Cervical incompetence (CI) is not an all or nothing phenomenon but a continuous variable. CI and preterm labor are not distinct entities but rather part of a spectrum leading to preterm delivery. Cervical length (CL) is an independent variable in the prediction of preterm delivery, to which it is inversely related. Application of a primary transvaginal cervical cerclage appears to be an unnecessary intervention in about 50% of women presenting with a history suggesting cervical incompetence. A better alternative for women with a history of or risk factors for CI is transvaginal ultrasonographic follow-up of CL. To facilitate the comparison of studies of CI, the authors suggest a nomenclature reflecting the different stages of prevention: primary, secondary, and tertiary transvaginal cervical cerclage.

The cervix and prematurity: aetiology, prediction and prevention

Preventing preterm delivery remains a major challenge for the 21st century. The cervix plays a fundamental role in supporting a pregnancy and preventing ascending infection from the lower genital tract. Infection is associated with early preterm delivery in about half of cases. Whatever the aetiology of preterm delivery, dilation of the cervix is a common endpoint, and transvaginal scanning of the cervix now provides a good predictor of early preterm delivery in both high- and low-risk women. Changes in the cervix are related to the detection of fetal fibronectin in the vagina, which is also an accurate predictor of delivery. However, the role of intervention in at-risk women is unclear. Elective cerclage is only effective in a minority of women, and the evidence to support its use is limited. It is currently being evaluated whether indicated cerclage, dictated by ultrasound findings, is beneficial.

Cervical surveillance as an alternative to elective cervical cerclage for pregnancy management of suspected cervical incompetence

OBJECTIVE

The aim of the present study was to compare the outcome of pregnancies among patients with suspected cervical incompetence treated either by elective cervical cerclage or an alternative management program involving cervical surveillance.

DESIGN, SETTING AND METHODS

A prospective cohort study was performed in two groups of patients at risk of cervical incompetence with singleton gestations attending the Royal Women's Hospital, Melbourne, Australia, from 1996 to 2000. The first group was managed by their obstetric carers with an elective cerclage, while the second group was managed conservatively as part of a cervical surveillance program offered to patients attending the Department of Perinatal Medicine for pregnancy care. This program consists of weekly visits from 16 weeks' gestation and involves alternating transvaginal ultrasound assessment of cervical morphometry with cervico-vaginal bacteriology and fetal fibronectin swabs. Empiric insertion of a cerclage is undertaken when there is evidence of significant cervical shortening (cervical canal <2.5 cm in length at </=24 weeks).

RESULTS

A total of 135 patients were identified for the study. Ninety-seven patients had an elective cervical cerclage inserted. Thirty-eight patients were followed through the cervical surveillance program. Twelve (32%) of the surveillance patients had a cerclage inserted at a mean gestational age of 20.6 weeks. There were no statistically significant differences between the groups in terms of maternal demographics or risk assessment scoring. One out of 38 (2.6%) patients of the surveillance group and 18/97 (18.6%) of the elective cerclage group delivered before 30 weeks' gestation (P = 0.034).

CONCLUSIONS

Our study suggests that by only inserting a cerclage when indicated on the basis of ultrasound assessment of cervical morphometry, the number of cerclages required can be reduced while the perinatal outcome is significantly improved.

Cerclage for prevention of preterm birth in women with a short cervix found on transvaginal ultrasound examination: a randomized trial

OBJECTIVE

The purpose of this study was to determine the efficacy of cerclage and bed rest versus bed rest-only for the prevention of preterm birth in women with a short cervix found on transvaginal ultrasound examination.

STUDY DESIGN

Women with > or =1 of high-risk factors for preterm birth (> or =1 preterm birth at < 35 weeks of gestation, > or =2 curettages, diethylstilbestrol exposure, cone biopsy, Mullerian anomaly, or twin gestation) were screened with transvaginal ultrasonography of the cervix every 2 weeks from 14 weeks of gestation to 23 weeks 6 days of gestation. Enrollment was offered to both asymptomatic women who were at high risk and who were identified to have short cervix (< 25 mm) or significant funneling (>25%) and nonscreened women who were at low risk and who were identified incidentally. The women who gave written consent were assigned randomly to receive either McDonald cerclage or bed rest-only. Both groups received similar counseling and treatment. Primary outcome was preterm birth at < 35 weeks of gestation.

RESULTS

Sixty-one women were assigned randomly. Forty-seven pregnancies (77%) were high-risk singleton gestations. Thirty-one women (51%) were allocated to cerclage, and 30 women (49%) were allocated to bed rest. There were no differences between the groups in demographic characteristics, risk factors, and cervical variables. Preterm birth at < 35 weeks of gestation occurred in 14 women (45%) in the cerclage group and in 14 women (47%) in the bed rest group (relative risk, 0.94; 95% CI, 0.34-2.58). There was no difference in any obstetric or neonatal outcomes. A subanalysis of singleton pregnancies with previous preterm birth at < 35 weeks of gestation and a short cervix of < 25 mm (n = 31 women) also revealed no significant difference in recurrent preterm birth at < 35 weeks of gestation (40% vs 56%; relative risk, 0.52; 95% CI, 0.12-2.17).

CONCLUSION

Cerclage did not prevent preterm birth in women with a short cervix. These results should be confirmed by larger trials.

Elective cervical cerclage versus serial ultrasound surveillance of cervical length in a population at high risk for preterm delivery

OBJECTIVE

To compare pregnancy outcome for women at risk of preterm delivery undergoing elective cervical cerclage in the first trimester or serial transvaginal assessment of cervical length with cerclage only if indicated (control cases).

DESIGN

A matched case control study.

SETTING

Prematurity clinic at two London teaching hospitals.

POPULATION

Women at high risk for preterm delivery.

METHODS

Cases of elective cervical cerclage were matched for maternal age, ethnic group, previous cervical surgery, previous second trimester loss and early preterm delivery to women undergoing serial ultrasound surveillance of cervical length. Pregnancy outcome data was collected. Data was analysed using Fisher's exact, Mann-Whitney and Student's t-tests.

MAIN OUTCOME MEASURES

Gestation at delivery, rate of delivery <24, 24-32 and 32-37 weeks gestation.

RESULTS

Thirty-nine cases of elective cervical cerclage were matched to control cases. Both groups were similar for maternal age, ethnic group, previous cervical surgery, previous second trimester loss and early preterm delivery. Cervical cerclage was performed in 14 (36%) of the control cases due to cervical changes. There was no significant difference in median gestation at delivery (266 days versus 260 days P=0.9), number delivering <24 weeks (15% versus 13% P=0.9), at 24-32 weeks (7.5% versus 15% P=0.6) and at 32-37 weeks (15% versus 13% P=0.9).

CONCLUSION

Serial transvaginal ultrasound surveillance of cervical length in women at high risk of preterm delivery appears to reduce cerclage rates without compromising pregnancy outcome. A large multicentered randomised trial is required to confirm these findings.

Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial

BACKGROUND

Cervical cerclage has been widely used in the past 50 years to prevent early preterm birth and its associated neonatal mortality and morbidity. Results of randomised trials have not generally lent support to this practice, but this absence of benefit may be due to suboptimum patient selection, which was essentially based on obstetric history. A more effective way of identifying the high-risk group for early preterm delivery might be by transvaginal sonographic measurement of cervical length. We undertook a multicentre randomised controlled trial to investigate whether, in women with a short cervix identified by routine transvaginal scanning at 22-24 weeks' gestation, the insertion of a Shirodkar suture reduces early preterm delivery.

METHODS

Cervical length was measured in 47?123 women. The cervix was 15 mm or less in 470, and 253 (54%) of these women participated in the study and were randomised to cervical cerclage (127) or to expectant management (126). Primary outcome was the frequency of delivery before 33 completed weeks (231 days) of pregnancy.

FINDINGS

The proportion of preterm delivery before 33 weeks was similar in both groups, 22% (28 of 127) in the cerclage group versus 26% (33 of 126) in the control group (relative risk=0.84, 95% CI 0.54-1.31, p=0.44), with no significant differences in perinatal or maternal morbidity or mortality.

INTERPRETATION

The insertion of a Shirodkar suture in women with a short cervix does not substantially reduce the risk of early preterm delivery. Routine sonographic measurement of cervical length at 22-24 weeks identifies a group at high risk of early preterm birth.

Effectiveness of cervical cerclage for a sonographically shortened cervix: a systematic review and meta-analysis

OBJECTIVE

The purpose of this study was to determine the effectiveness of cerclage for a shortened cervix on transvaginal ultrasound scanning in terms of the rates of preterm delivery and adverse neonatal and maternal outcomes.

STUDY DESIGN

Pre-MEDLINE and MEDLINE, EMBASE, and the Cochrane Library were searched for human studies that compared cerclage placement to no cerclage on the basis of transvaginal ultrasound findings of a short cervix (< or =2.5 cm). Two authors independently determined eligibility and abstracted data. Meta-analyses were conducted when possible.

RESULTS

Thirty-five studies were reviewed; 6 studies were eligible and were included in the analysis. There was no statistically significant effect of cerclage on the rates of preterm delivery (<37, <34, <32, and <28 weeks of gestation), preterm labor, neonatal mortality or morbidity, gestational age at delivery, or time to delivery. Birth weight was significantly higher with than without cerclage (P=.004).

CONCLUSION

The available evidence does not support cerclage for a sonographically detected short cervix. A randomized controlled trial is needed to determine whether this intervention will reduce adverse neonatal outcomes.

Development of a scoring system for predicting the risk of preterm birth in women receiving cervical cerclage

OBJECTIVE

To develop a model for identifying women receiving cervical cerclage at risk for spontaneous preterm birth <32 weeks.

STUDY DESIGN

Retrospective cohort study of high-risk patients based on past obstetric history. Our inclusion criteria involved all patients with singleton gestation who received cerclage between 10 and 24 weeks. They were evaluated for the risk factors associated with preterm birth <32 weeks. Risk factors evaluated include: indication for cerclage, gestational age at cerclage placement, cervical length prior to cerclage, timing of cerclage (emergency or elective) and route of cerclage (abdominal or vaginal). Univariable and multivariable analyses were used to determine the risk factors associated with preterm birth. A risk-scoring model was developed for the prediction of preterm birth <32 weeks in women receiving cerclage.

RESULTS

We identified 256 women receiving cerclage that met our inclusion criteria. Preterm births <32 weeks occurred in 51 (20%). Multivariable analysis revealed a cervical length <25 mm, a history of cone biopsy and emergency cerclage to be significant risk factors associated with preterm birth <32 weeks. The sensitivity, specificity, positive and negative predictive values of the best model for predicting spontaneous preterm birth <32 weeks in women with cerclage are 80%; 96%; 82% and 95%, respectively.

CONCLUSION

The presence of a short cervical length, a history of cone biopsy and emergency cerclage were associated with preterm birth <32 weeks. Our model had a high sensitivity for identifying women who may benefit from a closer surveillance.

Cervical cerclage in delayed interval delivery in a multifetal pregnancy: a review of seven case series

OBJECTIVE

To examine whether cervical cerclage after the first delivery prolongs the inter-delivery interval in delayed interval deliveries.

STUDY DESIGN

We identified 66 case reports and case series of delayed interval delivery published between 1880 and 2002. We selected seven case series that identified all cases of delayed interval delivery in their institutions during a specified period.

RESULTS

Despite routine use of broad-spectrum prophylactic antibiotics, the average incidence of clinical intrauterine infection after the first delivery was 36% (95% confidence interval (CI): 26-46%). The incidence of maternal sepsis was 4.9% (95% CI: 0.2-9.6%). Studies in which cerclage was infrequently used reported a shorter inter-delivery interval compared to studies where cerclage was used in all cases (median is equal to 9 days versus 26 days, respectively, P<0.001) despite similar gestational ages at the first delivery, types of antibiotics, tocolytics, and incidence of infection. After controlling for other factors, the use of cerclage did not significantly increase the risk of intrauterine infection (adjusted relative risk=1.1, 95% CI: 0.4-3.5).

CONCLUSION

Cervical cerclage after the first delivery is associated with a longer inter-delivery interval without increasing the risk of intrauterine infection.

Elective cervical cerclage for prevention of preterm birth: a systematic review

BACKGROUND

Elective cervical cerclage has been purported to prevent spontaneous preterm birth. We present a systematic review to determine the effectiveness of cervical cerclage in preventing spontaneous preterm birth before 34 weeks' gestation.

METHODS

Searches were conducted in MEDLINE, EMBASE, Cochrane Library, and Science Citation Index to identify randomized trials published between 1966 and 2002. All randomized trials that evaluated the effectiveness of elective cerclage compared with no cerclage in women who were at risk of preterm birth before 34 weeks' gestation were included for analysis. Quality assessment and data extraction were performed in duplicate.

RESULTS

There were seven relevant trials, comprising 2354 women. Meta-analysis was inappropriate because of large differences in the quality of the studies. However, in the largest single trial of good quality, cerclage was shown to prevent birth before 34 weeks' gestation. In this single study the reported number to be treated to prevent one additional preterm birth before 34 weeks was 24 women (95% CI: 10-61). The results of other trials were consistent with the finding of the largest trial. Data on complications were sparse and inconclusive.

CONCLUSION

Our systematic review shows that elective cervical cerclage has a significant effect in preventing spontaneous preterm birth before 34 weeks' gestation. Further research should focus on identification and quantification of possible complications, and of risk factors and tests that identify high-risk women who would benefit most from cerclage.

Current controversies in cervical cerclage

Cervical incompetence is defined as the inability to support a full-term pregnancy because of a functional or structural defect of the cervix. It is characterized clinically by acute, painless dilatation of the cervix usually in the mid-trimester culminating in prolapse and/or premature rupture of the membranes with resultant preterm and often previable delivery. Cervical cerclage has become the mainstay for the management of cervical incompetence, but remains one the more controversial surgical interventions in obstetrics. This article reviews the current state of the literature as regards the indications, contraindications, and techniques of cervical cerclage. This article also focuses in detail on 4 areas of controversy, namely transabdominal cerclage, cervical cerclage for a short cervix, the management of cerclage after preterm premature rupture of the membranes, and the utility of a second (salvage) cerclage.